豆知识 2010-12-19&12-25 认识IPv6 (1/2)

 IPVersion 6, or IPv6 for short, is a new version of the Internet Protocoldesigned to replace IPv4, the Internet Protocol¹ that is predominantly deployedand extensively used throughout the world. Although the exhaustion² of availableIPv4 address space has been the primary reason for the development of a newprotocol, the designers of IPv6 have added many new features and a number ofcritical improvements to IPv4. 

 

IPv4 hasstood the test of scaling an Internet work to a global utility, the size of theInternet today. But IPv4 wasn't initially³ designed to support a high number ofnetwork equipment. Because of the recent exponentialgrowth of the Internet, IPv4 is unable to satisfy the potential hugeincrease in the number of users or the geographical⁴ needs of the Internetexpansion. As a result, IPv4 address depletion⁵ is approaching quickly.Additionally, emerging applications such as Internet enabled PDAs, home area networks, mobile ad hocnetworks, IP wireless⁶ services and integrated IP telephony services require anew Internet protocol. 

 

The lifetimeof IPv4 has been extended using techniques such as address reuse with Network AddressTranslation or NET for short, Classless InterDomain Routing or CIDR andtemporary address assignments such as the Dynamic Host Configuration⁷ Protocolor DHCP. 

 

Thesetechniques appear to increase the address space and satisfy the traditionalserver client setup, but they fail to meet the requirements of true network anduser mobility⁸. Applications need an increasing amount of bandwidth, while address translation has a performance impact onthe network equipment. 

 

Next theneed for always-on environments to be contactable prohibits these IP addressconversion pulling and temporary allocation techniques. Furthermore, the plug-and-play feature required byconsumer Internet appliances further increases the protocol requirements.Millions of new technology devices such as wireless phones, PDAs, cars and homeappliances will not be able to get global IPv4 addresses any longer. IPv4 willsoon reach the stage where choice has to be made between either newcapabilities or a larger network, but not both. In other words, we need a newversion of the IP protocol to provide new and enhanced features in addition tosolving the IP address exhaustion problem. That new version of IP is IPv6.

1 protocol   

n.议定书，草约，会谈记录，外交礼节

参考例句：

• We must observe the correct protocol.我们必须遵守应有的礼仪。
• The statesmen signed a protocol.那些政治家签了议定书。

2 exhaustion   

n.耗尽枯竭，疲惫，筋疲力尽，竭尽，详尽无遗的论述

参考例句：

• She slept the sleep of exhaustion.她因疲劳而酣睡。
• His exhaustion was obvious when he fell asleep standing.他站着睡着了，显然是太累了。

3 initially   

adv.最初，开始

参考例句：

• The ban was initially opposed by the US.这一禁令首先遭到美国的反对。
• Feathers initially developed from insect scales.羽毛最初由昆虫的翅瓣演化而来。

4 geographical   

adj.地理的；地区(性)的

参考例句：

• The current survey will have a wider geographical spread.当前的调查将在更广泛的地域范围內进行。
• These birds have a wide geographical distribution.这些鸟的地理分布很广。

5 depletion   

n.耗尽，枯竭

参考例句：

• Increased consumption of water has led to rapid depletion of groundwater reserves.用水量的增加导致了地下水贮备迅速枯竭。
• Farmers should rotate crops every season to prevent depletion of the soil.农夫每季应该要轮耕，以免耗尽土壤。

6 wireless   

adj.无线的；n.无线电

参考例句：

• There are a lot of wireless links in a radio.收音机里有许多无线电线路。
• Wireless messages tell us that the ship was sinking.无线电报告知我们那艘船正在下沉。

7 configuration   

n.结构，布局，形态，(计算机)配置

参考例句：

• Geographers study the configuration of the mountains.地理学家研究山脉的地形轮廓。
• Prices range from $119 to $199,depending on the particular configuration.价格因具体配置而异，从119美元至199美元不等。

8 mobility   

n.可动性，变动性，情感不定

参考例句：

• The difference in regional house prices acts as an obstacle to mobility of labour.不同地区房价的差异阻碍了劳动力的流动。
• Mobility is very important in guerrilla warfare.机动性在游击战中至关重要。